Future changes in precipitation extremes over China projected by a regional climate model ensemble

Abstract

China has experienced frequent extreme precipitation events (i.e., floods and droughts) in recent years, which have resulted in significant economic losses and irrevocable damages to human societies and natural ecosystems. How to adapt to the forthcoming and long-term changes in precipitation extremes has become the top priority of decision makers and resources managers for developing resilient communities and sustainable agroecosystems. This essentially replies on a better understanding of possible changes in the spatiotemporal characteristics of precipitation extremes from both short-term and long-term perspectives. To this end, future changes in precipitation extremes across China in response to global warming are investigated in this study through a regional climate ensemble modeling approach. Specifically, in order to reflect spatiotemporal variations and uncertainties in model physics, a perturbed-physics global climate model ensemble is used to drive the PRECIS regional climate modeling system to generate 25-km climate projections throughout the 21st century for the entire country of China. The validation results for the ensemble simulations over the historical period show that the PRECIS model performs reasonably well in reproducing the spatial patterns of observed precipitation extremes in most regions of China. The future projections of precipitation extremes suggest that there is very likely to be a continuously-increasing trend in the analyzed precipitation extreme indices (except for a slight decreasing trend in CDD). Particularly, higher rates of increase in these indices are expected to occur from the forthcoming decades to the middle of this century. The results also indicate apparent spatial variations in the projected changes of precipitation extremes. In general, absolute changes in northern regions are relatively small compared to the significant changes in southeastern regions, suggesting that more severe floods might be expected in the southeast while slight increases in precipitation in the north (especially the northwest) would lead to a relief to the droughts. However, the percentage changes are larger in north than south. Moreover, it is reported that the frequency and intensity of heavy rains across the country are projected to increase, implying that more frequent urban flooding would become a major challenge for developing resilient and sustainable communities in China. The changes in thermal (i.e., temperature) and dynamical (i.e., circulations) factors could be some physical reasons for the increase of intensity and frequency in future precipitation.